Solve the System of Nonlinear Equations by the Addition Method $$9 x ^ { 2 } + 8 x y = 64$$

Multiple Choice

Solve the system of nonlinear equations by the addition method. $$9 x ^ { 2 } + 8 x y = 64$$
$$x ^ { 2 } - x y = 9$$

A) $\left\{ \left( - \sqrt { 8 } , \frac { \sqrt { 8 } } { 8 } \right) , \left( \sqrt { 8 } , - \frac { \sqrt { 8 } } { 8 } \right) \right\}$
B) $\left\{ \left( - \sqrt { 8 } , - \frac { \sqrt { 8 } } { 8 } \right) , \left( \sqrt { 8 } , \frac { \sqrt { 8 } } { 8 } \right) \right\}$
C) $\left\{ \left( - \sqrt { 8 } , \frac { \sqrt { 8 } } { 8 } \right) , \left( \sqrt { 8 } , \frac { \sqrt { 8 } } { 8 } \right) \right\}$
D) { }